注浆锚杆对围岩加固作用机理及应用案例分析

不良地质条件下进行隧道开挖时,隧道围岩原有应力平衡状态遭到破坏,若控制不当,可能会引起隧道大变形等不良现象的发生。为进一步研究注浆锚杆在隧道开挖过程中的支护作用机理,以圆形隧道开挖过程为例,对其围岩塑性变形区域、围岩潜在破裂面等进行了分析计算,同时对锚杆阵列布置、锚杆有效长度等进行了优化设计,推导出了对应的计算公式。结合一个圆形开挖隧道的锚杆布设方式实例,考虑三种锚杆加固方案,对理论研究成果进行了验证,研究结果表明：(1)隧道围岩的拉应力会通过注浆锚杆向周围进行转移,以增强其开挖隧道围岩的抗压强度和弹性模量；(2)提高隧道围岩的抗压强度、弹性模量,可以有效地降低隧道的土压力和沿径向的变形,且可提高隧道开挖效率；(3)注浆锚杆对围岩的加固作用,受到锚杆材质、长度、抗拉强度、直径以及布设方式等多种因素的影响。

Action Mechanism and Applications of Surrounding Rock Reinforcement by Grouting Anchor

Stress - balanced state of tunnel surrounding rock will be destroyed, during tunnel excavation under adverse geological conditions, which will result in the occurrence of tunnel large deformation and other adverse events. For further study of grouting anchor supporting mechanism, analysis and calculation of plastic deformation zone and surrounding rock potential fracture surface had been done. Key parameter calculation formula of bolt arrangement and effective length was derived. Theoretical research results were verified by a case of anchor reinforcement in circular tunnel. The conclusions had been drawn that: (1)Tensile stress of surrounding rock will transfer to the surrounding through grouting anchor, improving the compressive strength and elastic modulus. (2)Earth pressure and radial deformation can be reduced by increasing of compressive strength and elastic modulus. (3)Reinforcement effect of grouting anchor will be affected by various factors, such as material, length, diameter, tensile strength, and so on.